Cardiff Blues lost their unbeaten record in the Guinness PRO12 as Leinster came from 10 points behind to win 16-13 at the Arms Park.
Blues' disappointment was compounded by the loss of three forwards, Sam Warburton, George Earle and Taufa'ao Filise, who all departed with injuries.
Gareth Anscombe was Blues' star scoring a splendid individual try, which he converted in addition to kicking two penalties, but Leinster secured victory as Johnny Sexton kicked three penalties and converted Rhys Ruddock's try.
Against the run of play, Leinster came close to opening the scoring in the 13th minute when Dan Leavy brushed aside Matthew Morgan's attempted tackle to crash over in corner. However the replays showed the flanker had put a foot in touch so the try was ruled out by the TMO.
In the build up, Warburton clashed heads with Josh van der Flier and the Wales captain was forced to leave the field with Josh Navidi coming on as a replacement.
Despite the try not being awarded, the visitors were able to maintain the pressure and Sexton secured the first points of the game with an easy penalty.
Minutes later the outside half missed a more difficult chance as his kick went badly astray before Anscombe levelled the scores with a penalty.
Cardiff suffered a second injury blow when lock Earle limped off to be replaced by Macauley Cook but they overcame this setback to score a splendid try.
Ruddock lost possession in a crunching tackle from Nick Williams and Blues capitalised when Anscombe burst through the home defence to run 40 metres to score. The outside half converted and added a second penalty for a 13-3 interval lead.
Blues made two further changes at half-time with the injured Filise being replaced by Scott Andrews while full-back Morgan was withdrawn for Dan Fish.
After the restart, Sexton reduced the arrears with another penalty before Ruddock crashed over from a driving line-out with Sexton's conversion putting the visitors back on level terms.
After Anscombe missed a penalty and Leinster introduced Jamie Heaslip, the visitors took the lead for the first time as Sexton slotted a penalty after Navidi was sin-binned for a deliberate off-side.
The hosts had a chance to secure a draw but they turned down a penalty opportunity in favour of an attacking line-out but Leinster survived a Blues onslaught to record a narrow win.